Helical drive



FIG. 1 is a top perspective view of a first embodiment of a helical drive according to the design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a middle side elevational view thereof;

FIG. 6 is a right side elevational view thereof; and

FIG. 7 is a bottom perspective view thereof.

FIG. 8 is a top perspective view of a second embodiment of the helical drive according to the design;

FIG. 9 is a top plan view thereof;

FIG. 10 is a bottom plan view thereof;

FIG. 11 is a left side elevational view thereof;

FIG. 12 is a middle side elevational view thereof;

FIG. 13 is a right side elevational view thereof; and,

FIG. 14 is a bottom perspective view thereof. 

CLAIM The ornamental design for a helical drive, as shown and described. 